Draft Control, will it save wood?

Well with a draft like that the next thing to check is temps in your chimney. If your temps are real high then your sucking the heat past the HX tubes and up the chimney. You set up a EKO by a few things Draft & Moisture in your wood so if you know both of these things you can really fine tune your boiler. If one of these changes then you have to adjust your settings. If today its cold and gusty and you running @ 0.15 and tomorrow its warm and calm and your draft is 0.05 then things have changed. This is something you have no control over(wind and temps). If you install a barometric damper now you can have the same draft all the time. Check out my youtube vid of my damper.

Hope this helps,

Rob

leatherguy said:

My old wood boiler had a griswold flap damper inside would that be all right, anybody have one in their setup?

Click to expand...

I wouldn't do it- here's why-

The old-tech solid fuel combustion appliances where those flap flue dampers were used worked on natural draft.

Newer units have a blower that is either pushing air into or pulling combustion byproduct out of the boiler's combustion zones.

With either type blower, if you have a restriction in the flue, you may pressurize the flue- which will create the opportunity for leakage of combustion byproducts into the surrounding area.

By contrast, a barometric damper works by allowing additional flow into the flue, such that it won't result in back pressure in the flue.

Some have raised potential concerns about whether a barometric damper's addition of cool air into a flue might cool the flue gases too much and result in other concerns arising out of that, but I am not aware of that having been encountered in practice. Barometric dampers were frowned upon with inefficiently-burning older wood units inasmuch as they would introduce air that could worsen a chimney fire. But with modern units, operated properly, you should not be getting any significant creosote build up in the flue.

PS: the nuisance that some have experienced with barometric dampers on a wood gasification boiler are that sometimes you can get brief pressure surges in the flue (such as when you add wood when there's more than a small bed of coals) that will blow back out the damper- resulting in noise, fly ash coming out through the damper, or even a bent hinge on the damper. It seems that the Europeans' damper designs are set up to firmly shut against backpressure, whereas the standard US ones (Field Controls) are not. Not everyone seems to run into this- it seems to vary not only with boiler type, but also chimney and wood variations. If you get the hang of not opening or reloading the boiler too early, that won't be a concern.

Trevor,

I did have that problem on my BD with a puff pushing my flap out and it stuck. I have since made a positive stop out of a small block of metal and taped it in place with metal tape.


Rob

taxidermist said:

Trevor,

I did have that problem on my BD with a puff pushing my flap out and it stuck. I have since made a positive stop out of a small block of metal and taped it in place with metal tape.

Rob

Click to expand...

Thanks Rob- I had a big 'whoomp' (from refilling the firebox too quickly) that actually slightly bent the pivot shaft on my damper (bent it back, no big deal, now wait longer to add wood). The European designed dampers such as Hannson has pointed us to are just plain better designed- the swinging plate is behind the face of the damper, so that it'll close up to and be stopped by it in the event of pressure in the flue. Too bad the shipping cost is probably prohibitive.